Determination of the Suitable Places to Extract Groundwater for Irrigation Using Analytical Network Process(Case study: Birjand Plain)

Groundwater is one of the most important water resources especially for irrigation in the east of Iran. So, it is important to note its water quality variation for deciding to manage it. To this end, the study were done to zone Birjand plain located at latitude between 32˚ 30’-33˚ 00’ N and longitude between 58˚ 45’-59˚ 41’ E. In order to achieve this goal, the required layers, Sodium adsorption ratio (SAR), total hardness (TH), sodium solubility percentage (SSP), residual sodium carbonate (RSC), permeability index (PI), magnesium adsorption ratio (MAR) and kellyes ratio (KR), were created at GIS. Then, these layers were weighed using analytical network process (ANP). The results revealed that 68.65% of the plain had moderately inappropriate quality. About 5.25 and 5.34% of the plain had appropriate (south-east) and very appropriate (part of central and west) quality, respectively. The worst quality was determined in the south-west side of the plain so that it covered about 13.77% of Birjand area. According to the results, it is recommended to develop well digging in the east and south side of this plain.